JP2004011300A - PC composite structure, PC bridge and method for introducing prestress - Google Patents

Abstract

An object of the present invention is to prevent peeling at a boundary surface between a steel frame and a concrete structure portion of a PC composite structure, thereby improving structural strength.
A steel reinforced concrete composite in which a steel structure 20 and a reinforced concrete structure 30 are integrally joined, a PC steel material 40 for applying a compressive force to the steel reinforced concrete and introducing prestress into the steel reinforced concrete composite, At the point of introduction of the prestress, it is arranged between the PC steel material 40 and the steel reinforced concrete composite, abuts on both the steel structure part 20 and the reinforced concrete structure part 30 of the steel reinforced concrete composite, and reduces the compressive force of the PC steel material 40. A support plate 50 is provided to both the steel structure 20 and the reinforced concrete structure 30.
[Selection diagram] FIG.

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a PC composite structure, a bridge, and a method for introducing a prestress, and more particularly, to a PC composite structure in which a prestress is introduced into a composite of concrete and steel, and the use of such a PC composite structure. And a method of introducing prestress for building a PC composite structure.
[0002]
[Prior art]
Prestressed concrete (PC) structures are widely used in various civil engineering buildings. For example, a bridge, a water storage tank, and the like are included.
The basic form of the PC structure is that a PC steel material made of high-strength steel or the like is inserted into a sheath tube embedded in a concrete structure, and a large tensile force is applied to both ends of the PC steel material, so that a tensioned PC steel is formed. After fixing both ends of the steel material to the concrete structure, the tensile force is released. Due to the restoring force of the PC steel material, a compressive force is applied to the concrete structure, and a stress in the compression direction, that is, a prestress is introduced.
[0003]
Concrete is inherently strong in compression but relatively weak in tension. When a prestress such as described above is introduced into a concrete structure, when a tensile force is applied to the concrete structure, the tensile force is offset by the prestress in the compression direction previously introduced. Since the tensile stress generated in the concrete structure is reduced, the structural strength or durability is greatly improved.
Further, there is also known a technique for improving a structural strength by embedding a steel frame constructed by assembling steel materials or the like in a concrete structure. Such a composite of a concrete structure and a steel frame, in which prestress is introduced into the concrete structure, is referred to as a PC composite structure.
[0004]
[Problems to be solved by the invention]
However, in the PC composite structure, peeling may occur between the steel frame and the concrete structure. In particular, when a large prestress is introduced, there is a problem that peeling easily occurs between the steel structure and the concrete structure.
At the stage where prestress is introduced into the concrete structure, or in the use state of the PC composite structure, the deformation behavior of the concrete structure and the steel frame at the boundary is deviated, and peeling at the boundary surface occurs. It is guessed.
If both means of reinforcing a concrete structure, that is, a composite with a steel frame, and a method of introducing prestress are used together, both functions cannot be fully utilized.
[0005]
An object of the present invention is to solve the above problems, prevent peeling at the interface between the steel frame of the PC composite structure and the concrete structure, and improve the structural strength.
[0006]
[Means for Solving the Problems]
A PC composite structure according to the present invention includes a steel reinforced concrete composite in which a steel structure and a reinforced concrete structure are integrally joined, and a prestress is introduced into the steel reinforced concrete composite by applying a compressive force to the steel reinforced concrete composite. A PC steel material, disposed at the point of introduction of the prestress, between the PC steel material and the steel reinforced concrete composite, abutting on both the steel structure and the reinforced concrete structure of the steel reinforced concrete composite, A supporting plate is provided for transmitting the compressive force of the steel material to both the steel structure and the reinforced concrete structure.
[0007]
[PC composite structure]
Constructs structural members for various civil engineering buildings and equipment. Various shapes such as a flat plate shape, a curved plate shape, a column shape, a beam shape, a frame shape, a box shape, and the like can be taken according to the use and purpose.
The basic structure of the PC composite structure is a steel frame reinforced concrete composite composed of a steel frame portion and a reinforced concrete structural portion. By introducing a predetermined pre-stress with PC steel into the steel frame reinforced concrete composite, the PC composite structure is formed. Be a body.
(Steel-framed reinforced concrete composite)
<Steel structure part>
The steel structure is integrated with the reinforced concrete structure to form a steel reinforced concrete composite. The steel material has characteristics of being richer in toughness and stronger in tensile force than concrete, and thus has a function of reinforcing the reinforced concrete structure.
[0008]
The steel structure part is usually disposed in a steel frame reinforced concrete composite body, which is not exposed to the surface after construction and is located on the back side. However, there is also a form in which a part of the steel structure is exposed to a part of the steel reinforced concrete composite.
The steel structure is made of a steel material such as an H-beam or a C-beam, a steel bar, a steel plate, a hollow steel pipe, or the like. The arrangement of the steel materials is determined according to the shape and structure of the steel reinforced concrete composite. For connection between steel materials, bolts, rivets, welding, and other ordinary joining means are employed.
If a truss structure is constructed from steel, it will be a steel structure with excellent structural strength. It is effective for bridges.
[0009]
The steel structure can be provided with a mounting structure for the support plate, a sheath tube for PC steel, a mounting structure for concrete formwork, and the like. It is also possible to use a hollow steel pipe as the steel material constituting the steel structure part, and also use it as a sheath pipe for PC steel.
The steel structure may be built in advance before the steel reinforced concrete composite is constructed, or the construction of the steel structure may be sequentially advanced as the steel reinforced concrete composite is constructed. For example, when the steel-framed reinforced concrete composite is a bridge girder of a bridge, at the construction site, on the pier, the assembly and joining of the steel girder to be the steel structure portion and the formation of the reinforced concrete girder can be sequentially repeated to extend the bridge girder. .
[0010]
<Reinforced concrete structure>
Basically, the same material and structure as the ordinary PC structure can be adopted.
In a reinforced concrete structure, a reinforcing bar is embedded inside a concrete structure. The arrangement structure of the reinforcing bars can be appropriately set according to the load applied to the reinforced concrete structure.
The reinforced concrete structure is usually arranged in a portion of the steel-framed reinforced concrete composite exposed to the outer surface. The reinforced concrete structure may completely cover the entire steel structure, or a part of the steel structure may be left exposed.
[0011]
[PC steel]
Basically, the same material and structure as the PC steel material used in the ordinary PC composite structure can be adopted.
As the PC steel, a wire or a bar made of a material having excellent tensile durability, such as high-strength steel, is used. A single PC steel material can be constructed by arranging or bundling a plurality of wires or bars.
The PC steel material is arranged in a portion of the steel-framed reinforced concrete composite where a load in the tensile direction is greatly applied, and introduces a prestress in the compressive direction to that portion to reduce the load in the tensile direction.
[0012]
Therefore, the installation location and installation direction of the PC steel material, and further, the prestress introduction direction and the like are set in accordance with the distribution state of the load such as the bending moment force during the construction or use of the PC composite structure.
(Support plate)
It is located between the PC steel material and the steel reinforced concrete composite at the place where the prestress is introduced in the steel reinforced concrete composite. Usually, they are respectively arranged at opposing parts of a steel reinforced concrete composite. The opposing location is a location facing along the direction of introducing the prestress, and may be a location facing the outer surface of the entire outer shape of the steel reinforced concrete composite, that is, a facing surface, or in the middle of the steel reinforced concrete composite. , May be opposed to each other via a part of the steel-framed reinforced concrete composite.
[0013]
The support plate abuts on both the steel structure and the reinforced concrete structure. It may or may not be fixed to the steel structure or the reinforced concrete structure. At least it is sufficient if the surface pressure does not move in the direction parallel to the surface of the support plate, and the surface pressure is transmitted between the steel structure portion and the reinforced concrete structure portion in the surface direction of the support plate. The force does not have to be transmitted in the direction in which the bearing plate separates from the steel structure and the reinforced concrete structure, in other words, in the direction opposite to the direction in which the compressive force of the PC steel works.
In order to support the bearing plate on the steel structure, welding means such as welding, bolts, and rivets can be employed. Support by engagement or fitting may be used. A part of the supporting plate may be in contact with a part of the steel structure part so that the pressure can be transmitted in the plane direction.
[0014]
In order to support the supporting plate on the reinforced concrete structure, the supporting plate may be merely in contact with the outer surface of the reinforced concrete structure, or a part or the whole of the supporting plate may be embedded in the reinforced concrete structure. If a support plate is mounted in the form when the reinforced concrete structure is cast, the reinforced concrete structure is hardened and supported integrally.
As the material of the support plate, a steel plate having excellent mechanical strength such as rigidity and toughness can be used.
The shape of the support plate may be any shape as long as necessary surface pressure can be efficiently transmitted, and various shapes such as a rectangle, a polygon, a circle, an oval, and an ellipse can be adopted. The support plate may be a simple flat plate, or may be reinforced by providing a rib or a frame on the flat plate. Anchor protrusions and irregularities for improving the integration with the reinforced concrete structure may be provided on the contact surface with the reinforced concrete structure.
[0015]
The thickness and area of the support plate are set so that necessary surface pressure can be transmitted. It corresponds to the magnitude of the prestress introduced into the PC steel material arranged adjacent to the supporting plate.
[Introduction of pre-stress]
The work of introducing prestress into a steel-framed reinforced concrete composite using a PC steel material can basically employ the same materials, equipment, and work procedures as those of a normal PC composite structure.
At the place where the prestress is introduced or the place where the PC steel material is installed, the supporting plate is arranged at each of the opposed places of the steel reinforced concrete composite. The support plate comes into contact with both the steel structure and the reinforced concrete structure.
[0016]
A PC steel material is inserted through the opposite part of the steel reinforced concrete composite and placed. If there is a sheath tube or sheath space that penetrates the inside of the steel reinforced concrete composite, the PC steel material is passed therethrough. In some cases, the PC steel material is arranged along the surface of the steel reinforced concrete composite.
Apply tensile force to PC steel. As a means for applying a tensile force, a normal jack device or a traction device is used.
After the compressive force of the PC steel is transmitted to the support plate by, for example, supporting both ends of the PC steel to which the tensile force is applied on the support plate, the tensile force applied to the PC steel is released. The transmission of the compressive force between the PC steel and the supporting plate does not require joining the PC steel to the supporting plate so that the restoring force in the compression direction of the released PC steel is applied to the supporting plate. It just needs to be. Specifically, it is sufficient that the fixture made of the PC steel material comes into contact with the support plate and presses the support plate.
[0017]
A compressive force is applied to both the steel structure portion and the reinforced concrete structure portion of the steel reinforced concrete composite from the PC steel via the support plate, and a prestress in the compression direction is introduced into the steel reinforced concrete composite. The prestressed steel reinforced concrete composite, ie, the PC composite structure, has a significantly increased structural strength than before the prestress was introduced.
[Use of PC composite structure]
The PC composite structure having the structural strength increased more than that of the ordinary steel frame reinforced concrete composite can be applied to a structure subjected to a large load in various civil engineering and building structures.
[0018]
For example, in addition to bridges, civil engineering structures such as dams, embankments, roads, towers, tanks, and other structures are used as structures such as outer walls, roofs, floorboards, and columns.
[PC bridge]
The PC bridge is a bridge in which a bridge girder is erected between a plurality of piers, and includes a PC composite bridge girder composed of the above-described PC composite structure as a bridge girder.
The type of bridge is not particularly limited. Depending on the purpose of use, there are road bridges, railway bridges, road and railway combined bridges, and the like. Due to structural differences, there are continuous girder bridges, viaducts and arch bridges.
[0019]
The basic structure of a bridge is composed of piers arranged at regular intervals and bridge girders bridged between the piers. At both ends of the bridge, abutments that connect to the ground surface will be installed instead of ordinary piers. The structure that supports the bridge girder, including the abutment, is called the pier. The space between the piers is called span.
As the bridge girder, there are a case where an independent bridge girder is erected for each span, and a case where a continuous bridge girder is spanned for a plurality of spans. When the entire bridge is composed of a single continuous girder, it may be composed of continuous girder or simple girder divided into multiple sections or a combination of continuous girder and simple girder . The PC composite bridge girder can be used for the whole or a part of the bridge girder constituting the bridge, and also for the whole or a part of the continuous girder or the simple girder.
[0020]
[Construction of PC bridge girder]
The construction of a PC bridge girder usually includes a construction process of a steel girder, a construction process of a reinforced concrete girder, and a process of introducing a prestress using a PC steel material and a supporting plate. Some or all of these steps may be performed at the construction site, or may be performed at a different factory from the construction site.
The steel girder can be constructed at the factory for the entire length of the bridge girder, or a bridge girder block in which the bridge girder is divided into a plurality of blocks can be manufactured, and the bridge girder block can be assembled at the construction site.
[0021]
A reinforced concrete girder is constructed by setting a formwork in a state where a steel girder is embedded, arranging a reinforcing bar in the formwork, casting concrete and hardening the concrete. Reinforcing bars can be provided before or simultaneously with the installation of the formwork. These operations may be performed in advance at a factory or the like, and a composite body in which the steel girder and the reinforced concrete girder are integrated may be carried into the construction site, or the formwork may be applied to the completed steel girder at the construction site. It is also possible to construct a reinforced concrete girder by installing, arranging reinforcing bars and placing concrete. When building a reinforced concrete girder, a support plate can be attached.
The introduction of prestress using PC steel may be applied to the bridge girder made of steel-framed reinforced concrete composite at the stage of production at the factory, or the prestress may be appropriately adjusted as the construction of the bridge girder progresses at the construction site An introduction can also be made. In the case of a bridge girder, the magnitude and direction of the load such as the moment force applied to the pier position and the center position of the span vary depending on the location, and the magnitude direction of the load may change during the construction work. Therefore, appropriate prestress is introduced at each position and stage according to the construction position of the bridge girder and the progress of the construction work.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
[PC bridge]
The embodiment shown in FIG. 1 is a PC bridge composed of a PC composite structure.
As shown in FIG. 1A, a PC bridge is composed of three piers 10 of A, B, and C installed at intervals and a PC bridge girder 12 continuously bridged between the piers 10. And The details of the support structure of the PC bridge girder 12 for each pier 10 are not shown, but the PC bridge girder 12 is hingedly supported on the center pier 10 (B), and the left and right piers 10 (A) (C). ) Is supported by rollers.
[0023]
The PC bridge girder 12 has a steel girder 20 which is a steel structure part constructed by assembling steel materials in a box shape, and a reinforced concrete girder 30 which is a reinforced concrete structure part covering the steel girder 20.
FIG. 1B shows the distribution of the moment force acting on the bridge of FIG. 1A. The PC bridge can be considered as a continuous beam that has support points at three points A to C mechanically and is uniformly loaded over its entire length. The moment force shows the maximum value at the support point B. In the middle of each of the spans AB and BC, there is also a region where a moment force in a direction opposite to that of the support point B acts. This state does not include the effect of introducing prestress.
[0024]
[Construction of PC bridge]
As shown in FIG. 2, when constructing a bridge, first, piers 10 are constructed at predetermined intervals. A steel girder 20 is erected on the pier 10. A reinforced concrete girder 30 is formed around the steel girder 20 by casting in place. For forming the reinforced concrete girder 30, a formwork and a reinforcing bar supported by the steel girder 20 are installed around the steel girder 20, concrete is poured into the formwork, and after the concrete is hardened, the formwork is removed. The total length of the bridge is divided into a plurality of sections, and a reinforced concrete girder 30 is formed for each divided section.
When forming the reinforced concrete girder 30 for each divided section, starting from the position of the pier 10, new reinforced concrete girder 30 is added to both sides thereof. At the position of the pier 10, the construction work of the reinforced concrete girder 30 such as carrying in and setting of the formwork, arranging the reinforcing bar, and placing the concrete is easy. After the reinforced concrete girder 30 is formed at the position of the pier 10, the work of adding the reinforced concrete girder 30 to both sides thereof can be performed with good workability because the reinforced concrete girder 30 formed earlier can be used as a scaffold. If the load of the reinforced concrete girder 30 is equally applied to the left and right of the pier 10, the uneven load is not applied to the pier 10.
[0025]
Each time the formation of the divided reinforced concrete girder 30 as described above is completed, necessary prestress is introduced in accordance with the magnitude and direction of the load due to the moment force applied to that part.
[Introduction of pre-stress]
Prestress is introduced into a bridge having the above-described moment distribution in a direction to cancel the moment force. In particular, the tensile force acting on the reinforced concrete girder 30 is reduced to reinforce the reinforced concrete girder 30 that is weak in tensile force.
As shown in FIG. 3, when the reinforced concrete girder 30 is formed at the center pier 10, that is, at the support point B, prestress is introduced into the reinforced concrete girder 30 and the steel girder 20 in this portion.
[0026]
As is clear from FIG. 1B, the moment force applied to the support point B acts as a tensile force on the upper side and compresses on the lower side with respect to the composite structure including the reinforced concrete girder 30 and the steel girder 20. Acts as a force. In order to reinforce concrete which is relatively weak in tensile force, prestress is introduced so as to cancel the tensile force acting on the upper side.
The PC steel material 40 is inserted through the reinforced concrete girder 30 and the steel girder 20. With strong tensile force applied to the PC steel material 40, both ends of the PC steel material 40 are fixed to the end face of the reinforced concrete girder 30 with the fixing tool 44 via the supporting plate 50. When the tensile force applied to the PC steel material 40 is removed, the restoring force of the PC steel material 40 acts in the direction of compressing the reinforced concrete girder 30, and a prestress in the compression direction is introduced into the reinforced concrete girder 30.
[0027]
At this time, by using the support plate 50, the prestress by the PC steel material 40 is applied not only to the reinforced concrete girder 30 but also to the steel girder 20, as described in detail below.
[Detailed structure of support plate]
As shown in FIG. 4, the reinforced concrete girder 30 is formed so as to cover the steel girder 20 assembled with a steel material 22 such as a T-section steel.
<Tension side>
On the upper side of the reinforced concrete girder 30, the PC steel material 40 is inserted from both ends of the reinforced concrete girder 30 into the inside. The PC steel material 40 is inserted into a sheath tube (not shown) embedded in the reinforced concrete girder 30 in advance. Fixtures 44 of the PC steel material 40 are arranged on both end surfaces of the reinforced concrete girder 30. A support plate 50 is sandwiched between the fixing tool 44 and the end face of the reinforced concrete girder 30.
[0028]
The support plate 50 is made of a steel plate or the like, and has a rectangular plate shape as shown in detail in FIG. The bearing plate 50 is fixed to a steel material 22 such as a T-beam or the like constituting the steel girder 20 by welding or the like. A reinforcing plate 52 is attached between the support plate 50 and the steel member 22 to strengthen the attachment of the support plate 50 to the steel member 22 and prevent the support plate 50 from being deformed. Further, also on the inner side of the reinforced concrete girder 30, the reinforcing plate 54 is attached to the supporting plate 50 and is embedded in the reinforced concrete girder 30.
Before the reinforced concrete girder 30 is cast, the supporting plate 50 is attached to the steel girder 20, and a formwork is installed outside the supporting plate 50 to inject concrete, whereby the reinforced concrete girder 30 is cast. Can be integrally joined to the end face.
[0029]
In the state where the support plate 50 is arranged, the work of introducing the prestress by the PC steel material 40 is performed. The compressive force of the PC steel material 40 is applied to the end surface of the reinforced concrete girder 30 from the fixture 44 via the support plate 50 and also to the steel girder 20 via the joint with the support plate 50.
Therefore, the reinforced concrete girder 30 and the steel girder 20 are integrally compressed and deformed. At the boundary surface between the reinforced concrete girder 30 and the steel girder 20, both are integrally deformed, so that they are prevented from being peeled off or excessive stress is generated at the boundary surface. Prestress is introduced into both the reinforced concrete girder 30 and the steel girder 20.
[0030]
<Compression side>
In FIGS. 3 and 4, the supporting plate 60 is also arranged on the lower side of the reinforced concrete girder 30. A compressive force acts on the lower side by the moment force.
As shown in detail in FIG. 5B, the supporting plate 60 on the lower side is also joined to the steel material 22 by welding or the like. A reinforcing plate 62 is also mounted between the support plate 60 and the steel member 22.
However, since the PC steel material 40 is not disposed at the position of the support plate 60, there is no effect of introducing the prestress of the PC steel material 40 into both the reinforced concrete girder 30 and the steel girder 20.
[0031]
When the support plate 60 is disposed, the integrity of the reinforced concrete girder 30 and the steel girder 20 can be enhanced, so that the reinforced concrete girder 30 and the steel girder are subjected to external force applied during the subsequent work and after use in the construction. When the action of peeling off the boundary surface with the reinforced concrete girder 20 occurs, the integrity of the reinforced concrete girder 30 and the steel girder 20 can be ensured.
<Placement of support plate by location>
As described above, when the reinforced concrete girder 30 at the position of the pier 10 is formed, the supporting plate 50 is arranged on the upper side to introduce the prestress by the PC steel material 40, and the supporting plate 60 is arranged on the lower side. However, the arrangement of the support plates 50 and 60 and the position where the prestress is introduced change depending on the construction stage of the bridge or the position of the reinforced concrete girder 30.
[0032]
For example, in FIG. 1, a moment force causes a compressive force to act on the upper side and a tensile force to act on the lower side, on the reinforced concrete girder 30 at an intermediate position between the spans AB. Therefore, it is better to introduce a prestress in the compression direction by the PC steel material 40 to the lower side of the reinforced concrete girder 30 in this portion, contrary to FIGS. The support plate 50 is also attached to the lower side, and the support plate 60 is attached to the upper side. However, since the tensile force applied to the reinforced concrete girder 30 at this position is smaller than that at the position B of the pier 10, the prestress introduced by the PC steel material 40 may be small.
Since the prestress introduction to the intermediate position between the spans AB is performed at the stage where the reinforced concrete girder 30 is sequentially extended from the position of the pier 10 and constructed, the prestress introduction to the intermediate position between the spans AB is as follows. The compressive force applied to the lower side also applies a compressive force to the lower side of the reinforced concrete girder 30 existing at the location of the pier 10. At this time, if the support plate 60 is arranged on the lower side at 10 piers, the compressive force uniformly applies the compressive force to both the steel girder 20 and the reinforced concrete girder 30 at the 10 piers via the support plate 60. The communication function is exhibited.
[0033]
At positions other than the above, depending on the magnitude and direction of the moment force applied to that position, the arrangement of the support plates 50 and 60 and the PC steel material 40 and the magnitude of the pre-stress introduced by the PC steel material 40 are appropriately set, so that the steel The displacement stress at the interface between the girder 20 and the reinforced concrete girder 30 can be reduced.
[0034]
【The invention's effect】
In the PC composite structure according to the present invention, the prestress introduced into the steel reinforced concrete composite by the PC steel material is simultaneously applied not only to the reinforced concrete structure but also to the steel frame, so that the reinforced concrete structure and the steel frame are integrated. It does not deform excessively and does not generate excessive displacement stress at the boundary between the reinforced concrete structure and the steel frame structure.
As a result, it is possible to solve the conventional problems that the reinforced concrete structure and the steel frame structure are easily peeled off or the structural strength is reduced by the introduction of the prestress.
[0035]
Functions such as deformation prevention and strength improvement of the steel-framed reinforced concrete composite by introducing prestress can be exhibited more effectively.
[Brief description of the drawings]
FIG. 1 is a schematic structural diagram (a) and a moment distribution diagram (b) of a PC bridge representing an embodiment of the present invention.
[Fig. 2] Schematic structural diagram during construction [Fig. 3] Schematic structural diagram in a pre-stress introducing state [Fig. 4] Detailed structural cross-sectional view in a pre-stress introducing state [Fig. 5] Front structural diagram of a supporting plate [Explanation of reference numerals]
DESCRIPTION OF SYMBOLS 10 Bridge pier 20 Steel girder 22 Steel material 30 Reinforced concrete girder 40 PC steel material 44 Fixture 50, 60 Support plate

Claims (3)

A steel-framed reinforced concrete composite in which the steel frame structure and the reinforced concrete structure are integrally joined,
A PC steel material for applying a compressive force to the steel reinforced concrete composite to introduce prestress into the steel reinforced concrete composite,
At the point of introduction of the prestress, it is disposed between the PC steel material and the steel reinforced concrete composite, abuts on both the steel structure and the reinforced concrete structure of the steel reinforced concrete composite, and compresses the PC steel. A support plate that transmits the pressure to both the steel frame structure and the reinforced concrete structure,
A PC composite structure comprising: A bridge in which a continuously or separately constructed bridge girder is erected over a plurality of piers,
A PC bridge comprising a PC composite bridge girder comprising the PC composite structure according to claim 1 in at least a part of the bridge girder. A method of introducing prestress into a steel reinforced concrete composite in which a steel structure and a reinforced concrete structure are integrally joined,
(A) arranging a supporting plate at the point of introduction of the prestress, which abuts on both the steel structure and the reinforced concrete structure of the steel reinforced concrete composite;
(B) inserting a PC steel material into the steel reinforced concrete composite at the point of introduction of the prestress;
(C) applying a tensile force to the PC steel;
After supporting both ends of the PC steel material to which the tensile force is applied to the supporting plate, the tensile force is released, and both the steel structure portion and the reinforced concrete structure portion of the steel reinforced concrete composite from the PC steel material via the supporting plate. (D) introducing a prestress into a steel reinforced concrete composite by applying a compressive force to the steel composite.

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